Silencer



Patented July 21, 1942 SILENCER John P. Tyskewicz, Hartford, Conn.,assignor to The Maxim Silencer Company, Hartford, Conn, a corporation ofConnecticut Application November 7, 1940, Serial No. 364,695

14 Claims.

This invention relates to silencers for use with internal combustionexhausts and intakes, air compressor intakes and discharges, and otherinstallations. It has particular utility when both noise and a pulsatinggas flow are present.

It has hitherto been proposed to constructing effects, they havepresented difiiculties in the production of so-called shell noise, dueto the shock-excitation of vibrations in the walls of the silencer, andhave in some cases offered without apparent cause a relatively highback-pressure to the engine exhaust.

I have found that greatly improved results will be obtained in silencingeffect, reduction of shell noises, and diminution of back pressure, by arearrangement of the disposition of the pipes within the chamber. Inprior practice each pipe has extended into the chamber from abouthalf-way up to a point fairly close to that end of the chamber oppositethat from which the pipe entered. In accordance with the presentinvention at least one of the pipes is retroverted or recurved so thatit terminates close to th end of the chamber through which it entered.The pipe, which is provided with lateral escap openings distributedthroughout its length, gives the gas Pulses a greater chance to bleedoff through these openings than the much shorter tubes previous'ly used.This improves the silencing effect and reduces the tendency to produceshell noise. The added length of tube which is provided with lateralopenings also greatly reduces the tendency of the exhaust line toresonate at particular frequencies and makes the positioning of thesilencer in the exhaust line non-critical. These improvement areapparently accentuated, without increasing back-pressure, by the curvedpath which the gas must take in passing through the pipe.

by the discharge or the gas through the open end of the pipe at a pointat a distance from the entrance wall substantially on the order of thediameter of th pipe, a distance equa1 to sixiifths of the pipe diameterappearing to give optimum results. The entering gas thu has noopportunity to exert by its flow past the outlet Th back pressure of thedevice is kept down flow, as has been the case in some priorconstructions.

In many cases it will be sufficient to have one pipe only within achamber, th chamber leading into an exhaust pipe or a second chamberthrough one or more perforations in its walls. This permits a longerlength of pipe within the chamber than if room had to be found for tworecurved pipes, which, due to practical limitations on the diameter ofthe chamber and the necessity of preserving a volume for expansionoutside the pipes, can in general not be arranged side by side.

The invention will now be described With reference to the variousembodiments shown in the accompanying drawings, in which:

Fig. 1 is a median section through a twochamber cylindrical silencerconstructed in accordance with one form of the invention;

Figs. 2, 3, and 4 are similar views showing modifications;

Fig. 5 is a median section through one form of single chamber silencer;

Fig. 6 is a median section through a modified form of two-chambersilencer;

Fig. '7 is a section on line 1-1 of Fig. 6;

Fig. 8 is a median section through a twochamber silencer intendedparticularly for use where it is necessary to cool the exhaust gases bythe injection of water;

Fig. 9 is a median section through a twochamber silencer constructed inaccordance with the invention but utilizing different mechanicalfeatures which have certain advantages in the building of the silencer;

Fig. 10 is a section on line l0 l0 of Fig. 9;

Fig. 11 is a single-chamber silencer constructed in accordance with themechanical principle of Fig. 12 is a section on line l2--I2 of Fig. 11;

Fig. 13 is a fragmentary view showing an alternative Way of forming theopen end of the conducting tube;

Fig. 14 is a fragmentary median section showing a single-chambersilencer in which both inlet and exhaust pipes enter from the sam end;and

Fig. 15 is a diagrammatic view of a threesection silencer.

The silencer shown in Fig. 1 has a casing IS with end headers I1 and II.This casing is preferably made cylindrical for ease in manufacture.Through the header ll enters a pipe l8 which is retroverted or recurvedupon itself as at l9, and which has an open end 20 positioned a distancetube a suction action tending to prevent outfrom the header I! on theorder of the diameter of the tube. Preferably the spacing between theopen end and the header is made six-fifths of the diameter as this hasbeen found to produce a minimum back pressure. The tube has arrangedalong its length a plurality of lateral escape Openings in the form orperforations 2| or slots such as ar shown in some-of the othermodifications. The casing is divided by a partition 22, thus forming achamber 23 into which the pipe I8 extends and a chamber 24 into which apipe 25 extends. The partition is provided with a central perforation 26preferably guarded by a baffle 21 held on posts 28 to cause dispersionof any slugs of gas that might otherwise tend to pass through thecentral opening, The pipe 25 extends through the partition l1 and. isrecurved upon itself and provided with lateral openings similarly to thepipe I8. The partition 22 should be located so that the two chambers 23and 24 are of unequal lengths, preferably having a non-integral relationwith respect to each other as it has been found that this proportioningof the chambers avoids the tendency to pass through the device certainfrequencies forming normal modes of vibration of th gas longitudinallyof the chamber. The operation of this device has been discussed aboveand need not be repeated.

Fig. 2 shows a somewhat similar device in which similar parts have beendenoted by the same reference characters. The difference between thisdevice and that shown in Fig. 1 is that the partition 22 has beenreplaced by a partition 38 through which a tube 3| passes, the tubehaving recurved ends 32 and 33 located within the chambers 23 and 24respectively. The open ends of this tube 3| are directed towards thepartition 36 and are spaced from it a distance preferably on the orderof the diameter of the tube. This tube, as well as the others, is

provided with lateral escape openings 34,

Fig. 3 shows a similar structure except that the tube 3| is replaced bya tube 35 having its open ends 36 directed toward the cylindrical wallof the container rather than toward the partition 30. This constructionhas somewhat higher back pressure than the device of Fig. 2 but iseasier to construct. The partition 36 has in this case been shiftedslightly to indicate that its position is not critical but in general itwill be found desirable to have greater dissimilarity between thelengths of the two chambers than is shown in Fig. 3.

Fig. 4-. illustrates a further form of the device in which one endconnection 40 to the interior of the casing 4| enters directly into oneof the two chambers 42 into which the casing is divided by a partition43-. In this case a tube 44 extends into the chamber 42 through thepartition 43 and has an open end 45 and lateral escape openings 46arranged as previously described. A second tube 41 enters the secondchamber 48 and is likewise provided with escape openings 49 and an openend 50.

Fig. shows a modification illustrating both a different type of" lateralescape opening and the adaptation of the silencer to a single chamberdevice. In this case one pipe 5| enters the chamber 52 at one end whilea second pipe 53 enters the chamber at the other end and is recurvedupon itself as at 54, terminating with an open end 55 spaced from theheader 56 a distance on the order of the diameter of the .pipe. In thisform the escape openings have been shown as composed of slots 51 formedin the straight parts of the tube and holes 58 'formed in the curvedparts. The acoustical performance of the two types of openings are thesame,

the chance for the gas to escape laterally from and into the pipe beingdistributed with practical uniformity along it length; but a slot issomewhat easier to machine in a straight tube than is a series of holes,the converse being true in curved portions.

Figs. 6 and 7 show a device having two chambers 66 and BI, into theformer of which extends a recurved pipe 62 provided with an open end andlateral escape openings as before. The chambers are separated by acentral partition 63 from which an off-center pipe 64 extends into thechamber 60. This chamber has an open end extending toward the center ofthe chamber 60 and has lateral escape openings 65 in its walls. Whilenot as eflicient as some of the other forms described, this type ofconstruction presents some constructural activities even to the pointwhere the tube 62 could be extended sufficiently to overlap the tube 64partially without too much decrease in the free volume within thechamber 60. The recurved pipe 66 within the chamber 6| is in this caseconstructed as previously described.

In Fig. 8 I have shown in median section a silencer intended for usegenerally on shipboard where it is desirable to flood the silencer withwater in order to cool the gases and extinguish any sparks. The casing10 is in this case divided into chambers H and 12 by a partition 13which, as in other cases, is preferably disposed off-center of thelength of the casing. An inlet pipe l4 enters the chamber ll and isrecurved upon itself at 75, being provided with lateral escape openings'16 and an open end 11. In addi tion the two limbs of the curved pipeare preferably connected by short pipes 18 having lateral escapeopenings 79. These pipes not only permit even better evening out of thegas pulses :but add materially to the strength of the device. Thepartition 13 is pierced by a short tube having a lateral escape opening8| extending substantially throughout its length and is also pierced bya hole 82 provided for drainage at the bottom of the partition. Theexhaust pipe 83 extends into the casing tangent to its bottom and haswithin the casing a lateral escape opening 84. A water jet 85 enters thetube '14 in order to cool the exhaust gases and it will be observed thatdrainage is provided from all of the pipes and chambers out through theexhaust line 83.

Fig. 9 shows a structure acoustically similar to those previouslydescribed but having constructural advantages particularly desirable inthe larger sizes where it is difficult to bend the pipe. In this casethe casing 96 is divided into chambers 9| and 92 by a non-centralpartition 93, preferably disposed even further off-center than shown. Apipe 94 enters the casing through one. of its headers 95, beingpreferably arranged axially of the cylindrical casing. A pipe 96 alsoenters the chamber 9| through the partition 93. Both of these pipes havelateral escape openings 91 formed as a continuous slot. Around both ofthese pipes is a larger tube 98 having a slot 99 positioned in alignmentwith the slot 91 and a second slot I02 on the opposite side. The tube 98is preferably secured to the pipes 95 and 96 by welding at a pointadjacent the edge of the slot. It will be observed that the large tube98 can in this case be formed of a flat sheet bent into a cylinder andthat no bending of pipe forms is required. A partition I is providedintermediate the opposite ends of the pipes 94 and 96. The gas entersthrough the pipe 94 which has an open end at a distance from thepartition I00 substantially equal to the diameter of the pipe. Most ofthe gas turns back through the annular space I M between the pipe 94 andthe tube 98, although a part of it can pass out through the slots. Thegas then passes through the interior of the chamber III and by a reverseoperation enters the pipe 96 through which it passes into the chamber92, the construction of the parts in the latter chamber being the sameas in the chamber 9|, no detailed discussion is necessary.

The structure shown in Figs. 11 and 12 is based upon the same generalprinciple as that shown in Fig. 9 but employs a smaller structure and alesser number of operations on the gas. In this case the chamber I hasan inlet conduit I05 extending into it at one end. This inlet conduithas at least a portion of its length within the chamber provided with aslot I01. Surrounding the conduit is a tubular member I08 having abottom I08 and a slot I I0 in registry with the slot I01 and a secondslot' I I4 on the opposite side. The conduit and the tubular member arepreferably secured to each other as by welding adjacent the edges of theslot. In this case the conduit I05 is shown as being positioned slightlyeccentric with respect to the casing in order to give a larger expansionspace at the side of the chamber remote from the slot. Here again theopen end III of the conduit and the open end II2 of the tube arepositioned at distances from the headers I09 and H3 on the order of thediameter of the conduit and tube respectively.

Fig. 13 shows a detail which may be applicable to any of the abovestructures. In this case the tube II5, extending within the casing III;and recurved upon itself, has one or more wedge shaped openings I I1formed in its end. This end is secured as by welding to the header I I8.This increases the rigidity of the structure and may in some case bedesirable, although the back pressure may be found to be greater thanwhere a clear spacing between the header and the end of the tube isused.

The structure of Fig. 14 utilizes a chamber I20 to which it is desiredto make inlet and outlet connections at one end only. One of the twoconduits I2I is formed with a reverse bend I22 and terminates with anopen end I23 adjacent the header I24. The second conduit I25 also entersthrough this header and 'extends throughout the length of the casing,having an open end I26 adjacent the opposite header I21. Both tubes areprovided with lateral escape openings I28 along the lengths as shown.

Fig. is in general similar to the structure of Fig. 3 but illustrateshow the invention may be adapted to a structure having more than twochambers. In this case one conduit I30 enters the first chamber I3I andis recurved upon itself as shown. The chamber I3I is joined to a chamberI32 by a U-shaped tube I33. A similar U-shaped tube I35 connects thechambers I32 and I34 and a recurved tube I36 extends from the chamberI35 to the outside. All tubes are provided with lateral escape openingsas indicated.

From the variou embodiments described it is believed that it should bepossible to design a satisfactory device for any intended use and withvarying manufacturing requirements in mind. These embodiments areillustrative only, and the scope of the invention is defined not by thembut by the appended claims.

I claim:

1. A silencer comprising a walled chamber and inlet and outlet passagesleading into the chamber, at least one of said passages comprising aconduit extending into the chamber, said conduit being retroverted andterminating in an open end near its entrance into the chamber and beingprovided with one or more lateral escape openings distributed along thelength of the conduit.

2. A silencer comprising a walled chamber and inlet and outlet passagesleading into the chamber, at least one of said passages comprising aconduit extending into the chamber, said conduit being retroverted andterminating in an open end near its entrance into the chamber at adistance from the adjacent chamber wall on the order of the diameter ofthe conduit, and also being formed with one or more lateral escapeopenings distributed along the length of the conduit.

3. A silencer comprising a tubular casing having end walls, and anopen-ended conduit extending through each end wall and formed with areturn bend terminating in an open-end adjacent the end wall throughwhich said conduit entered the casing and spaced therefrom a distance onthe order of the diameter of the conduit, each of said conduits beingformed with one or more lateral escape openings distributed along thelength of the conduit.

4. A silencer comprising a chamber, an inlet opening in one end and anoutlet opening in the other end thereof, and an open-ended conduitwithin the casing leading from the opening at one end of the casingtowards the other end of the casing, bending back upon itself, andextending towards the first end of the casing to a distance therefrom onthe order of the diameter of the conduit, said conduit having lateralescape openings formed in its wall.

5. A silencer comprising a chamber and a pair of open-ended tubeentering the-chamber and serving as inlet and outlet conduitsrespectively, at least one of the tubes being bent back upon itself, theopen ends of said tubes opening towards opposite ends of the casing andeach of said tubes having lateral escape openings formed in its walls.

6. A silencer comprising a chamber and a pair of open-ended tubeentering the chamber from opposite ends, inlet and outlet conduitsconnected to said tubes, each of said tubes being bent back upon itselfinto adjacency with the end of the chamber from which it entered thecasing, each of said tubes being sufficiently unrestricted in diameterto cause no restriction in gas flow as determined by said inlet andoutlet conduit, each of said tubes having one or more lateral escapeopenings in its wall distributed substantially throughout the course ofsaid tube Within the casing.

7. A silencer comprisinga chamber and a pair of open-ended tubesentering the chamber from opposite ends, inlet and outlet conduitsconnected to said tubes, each of said tubes being bent back upon itselfinto adjacency with the end of the chamber from which it entered thecasing, each of said tubes being sufficiently unrestricted in diameterto cause no restriction in gas flow as determined by said inlet andoutlet conduit, each of said tubes having one or more lateral escapeopenings in its wall distributed substantially throughout the course ofsaid tube within the casing, and an apertured partition interposedbetween the tubes.

8. A silencer having a plurality of open-ended tubes each bent uponitself, each tube having longitudinally distributed lateral escapeopenings formed in its walls, and a casing structure surrounding saidtubes and having wall members positioned to prevent direct passage ofgas between the open end of the tubes without passing throughsubstantially the length of the casing structure, whereby gas will passthrough one of said tubes, out through its open end and'lateral escapeopenings into the interior of the casing, and thence into the secondtube through its open end and lateral escape openings.

9. A silencer comprising a casing forming an internal chamber, a conduitextending into the chamber and having a slot along one side and an inneropen end, a tube surrounding said conduit and provided with a pair ofopposed slots, one of which is in register with the slot in the conduit,said conduit and tube being secured together adjacent the edges of saidregistering slot, a closure for the tube spaced from the end of theconduit a distance on the order of the diameter of the conduit, and asecond conduit extending into said casing.

10. A silencer comprising a casing forming an internal chamber, a pairof conduits entering the chamber from opposite ends thereof and spacedapart a distance on the order of twice the diameter of the conduits, theportion of each of said conduits within the chamber having a slot alongone side and an open inner end, a tube surrounding said conduits andprovided with a slot in register with the slots in the conduits and witha slot spaced therefrom, said conduits and tube being secured togetheradjacent the edges of the slots, and a partition secured interiorly ofthe tube intermediate-the ends of the conduits.

-11. A silencer comprising a chamber having a header at both ends, anopen-ended retroverted conduit entering the chamber through a header atone end, said conduit having an open end adjacent said header, and asecond conduit extending through the chamber andhaving an open endadjacent the header at the opposite end of the chamber, both of saidconduits having lateral escape openings in their walls distributed alongthe portions of said conduits within the chamber.

12. A silencer comprising a pair of longitudinally adjacent walledchambers, an open-ended, retroverted, laterally a'pertured inlet pipeextending through the outer end wall of one chamher and terminating withits open end adjacent said wall, an open-ended, retroverted, laterallyapertured outlet pipe extending through the opposite end Wall of thesecond chamber and terminating adjacent said end, and a laterallyapertured open-ended pipe' connecting the chambers and extendingsubstantially into at least one of them.

13. A silencer comprising a pair of longitudinally adjacent walledchambers, an open-ended, retroverted, laterally apertured inlet pipeextending through the outer end Wall of one chamber and terminating withits open end adjacent said wall, an open-ended, retroverted, laterallyapertured outlet pipe extending through the opposite end wall of thesecond chamber and terminating adjacent said end, and an open-ended,U-shaped, laterally apertured pipe connecting the chambers and havingits open ends directed towards the side walls thereof.

14. A silencer comprising a chamber, an openended pipe extending intothe chamber and bent upon itself to form two adjacent legs, conduitsconnecting the legs, and an outlet conduit extending from the casing.

JOHN P. TYSKEWICZ.

